I. Field of the Invention
The present invention relates generally to devices for measuring flow rates. More particularly, the present invention relates to a device and method for determining the flow rate of gas entrapped fluids delivered in a pulsating flow, such as milk wherein the invention boasts an improved fluid level detection arrangement for determining flow rates with improved accuracy, and an improved temperature sensing arrangement for determining the temperature of the gas entrapped fluid with improved accuracy.
II. Discussion of the Prior Art
In recent years, it has become increasingly important for farmers to monitor and document the productivity of the cows within a given herd so as to ensure that dairy operations are being conducted with the highest degree of efficiency. A principal indicator of productivity is milk output, that is, the amount of milk that each cow is capable of rendering over a given period of time. By monitoring the milk output of each cow, a farmer can maximize the total amount of milk generated by the entire herd by singling out low-producing cows and replacing them with cows having greater ability to provide milk. Moreover, in that milk output is related to the overall health of a cow, farmers may also reduce the likelihood of having "tainted" milk enter the main holding tank by removing the low-producing, potentially ill cows from the milking herd, thereby improving the overall quality of the milk within the holding tank. In order to properly monitor milk output, it is essential to determine the true flow rate of the milk being delivered. However, obtaining an accurate assessment of flow rate during milking operations is particularly challenging due to the turbulent, pulsatile nature of the milk flow, as well as the foaming which results therefrom.
U.S. Pat. No. 5,083,459, issued to Lind et al., illustrates an exemplary metering device for determining the flow rate of gas-entrapped fluids delivered in a pulsating flow, such as the milk rendered from cows during dairy operations. The flow meter of the '459 patent includes a multi-section, separable housing having a velocity reduction chamber for reducing the velocity of the incoming milk, a turbulence reduction chamber for reducing the amount of turbulence of the milk flow and for separating out foam, and a measurement chamber having a plurality of vertically spaced probe members for measuring the fluid level of the milk passing therethrough. More specifically, a "common probe" fluid level detection arrangement is employed, wherein a base probe is disposed proximate the bottom of the measurement chamber for receiving a driving signal and the upper probes are monitored the determine when conductivity is established between the base probe and any of the upper probes due to the rising and falling of the fluid within the measurement chamber. In this fashion, the fluid level within the measurement chamber can be continuously tracked and further correlated into flow rate such that the milk output for each cow within a herd may be monitored and documented.
Although the physical structure of the housing is highly successful in reducing the turbulent, pulsatile fluid flow into a manageable fluid stream, the above-identified "common probe" fluid level detection arrangement occasionally results in inaccurate fluid level assessments when high and low fluid levels exist within the measurement chamber. As will be appreciated by those skilled in the art, this stems from the fact that the base probe is common to all fluid level measurements. More particularly, the impedance between the base probe and each upper probe is unique and fixed such that the impedance associated with a particular fluid level is different than the impedance associated with other fluid levels. By basing each fluid level determination on different base probe-to-upper probe impedances, the sensitivity of the "common probe" fluid level detection arrangement varies depending upon the particular fluid level. In practice, the varying sensitivity of the "common probe" fluid level detection arrangement may cause it to fail to detect when continuity is established between the base probe and the upper probes at high fluid levels, as well as detect continuity between the base probe and upper probes at low fluid levels when in actuality continuity has not been established. Missing continuity "hits" and detecting false continuity "hits" in this fashion causes the resulting determination of flow rate to be inaccurate and therefore less valuable in monitoring milk production.
In addition to monitoring milk production, agriculturalists oftentimes find it helpful to monitor the temperature of each cow within a herd as a way to further ensure that the cows are in good health for optimizing the milk production of the herd. The traditional technique for assessing cow temperature requires manually inserting a thermometer in the rectum and/or vagina of the cow so as to obtain a direct assessment of body temperature. While this method does provide highly accurate cow temperature assessments, it is nonetheless is disadvantageously time consuming as well as undesirably messy. To avoid these drawbacks, various efforts have been undertaken to monitor cow temperature via indirect means so as to eliminate the need for manually inserting thermometers in the cows as described above. For example, in the system disclosed in the '459 patent to Lind et al., a temperature sensing element is typically inserted into the fluid line extending between the milk flow meter and the holding tank to monitor the temperature of the milk being extracted from each cow. Milk temperature, it is found, provides a general indication of the temperature of the cow being milked. While this method for indirectly monitoring cow temperature is generally useful, it is nonetheless flawed in that the temperature sensing element is positioned a fair distance from the actual cow and requires permanently altering the fluid line to insert the temperature sensing element therein. Disposing the temperature sensing element distal to the cow in this fashion subjects the temperature sensing element to fluctuations unrelated to cow temperature, such as temperature variations within the milking parlor, such that the resulting milk temperature measurements may not accurately reflect the true temperature of the cow. Permanently altering the fluid line results in increased costs in terms of both the time required to alter the fluid line, as well as the cost of material.
A need therefore exists for an improved flow meter having an improved fluid level detection arrangement capable of consistently rendering accurate fluid level assessments for reliable flow rate determination. A further need exists for an improved flow meter having an internally disposed temperature sensing element for providing milk temperature assessments which accurately reflect the actual temperature of the cow.